How changes in climate and agricultural practices influenced wheat production in Western Europe

Wheat is one of the main crops cultivated in nearly all regions of the world, from the equator to temperate lands. Since the early 1960s, grain yield has increased almost linearly. However, in several European countries, a stagnation is observed since the mid-1990s. Several studies have been carried out to analyse the possible causes of this stagnation, particularly in Western Europe and France. Three groups of factors are usually mentioned: a decrease in genetic progress, changes in agricultural practices for economic or regulatory reasons and, finally, more unfavourable biotic and abiotic environmental conditions. The vast majority of studies carried out in Europe and France show that the genetic progress has not slowed down since the 1980s. Among agricultural practices, a decrease in nitrogen fertilization and area of favourable preceding crops are often put forward. Finally, drought during the stem elongation and heat stress during grain-filling stages were mainly identified as environmental factors increasingly impacting yield. Besides average climate changes, extreme climatic years may have a large impact such as season 2015-2016 in France. Abnormally warm temperatures in late autumn, wet conditions and low solar radiations in spring explained this particularly low grain yield. Extreme events cause huge challenges to breeding that would require either adequate experimental conditions, trait assisted methods or genomic selection models that would enable to select for climatic scenarios that are very rare.